Reciprocating Saw Blade With Curved Cutting Edge

ABSTRACT

A reciprocating saw blade that includes an elongated blade body defining an inner end and a distal end, a cutting edge located on one side of the blade body and extending between the inner and distal ends thereof and a tang located at the inner end of the blade body. The tang projects from the blade body at an acute angle relative to a line tangent to an inner end of the cutting edge. The cutting edge includes a portion defining a substantially curved contour and optionally can include at least one further portion defining a non-curved contour.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 120 as acontinuation of U.S. patent application Ser. No. 15/661,703, titled“Reciprocating Saw Blade with Curved Cutting Edge,” filed Jul. 27, 2017,which is a continuation of U.S. patent application Ser. No. 14/213,503,now U.S. Pat. No. 9,757,807, titled “Reciprocating Saw Blade with CurvedCutting Edge,” filed Mar. 14, 2014, which claimed priority under 35U.S.C. § 119 to U.S. Provisional Patent Application No. 61/784,277,titled “Reciprocating Saw Blade with Curved Cutting Edge,” filed Mar.14, 2013, the entire contents of each of which is hereby expresslyincorporated herein by reference for all purposes.

TECHNICAL FIELD

This application relates to reciprocating saw blades, and moreparticularly, to reciprocating saw blades having an at least partiallycurved cutting edge.

BACKGROUND

A reciprocating saw machine is a power saw, often hand held, including achuck that releasably engages one end of a reciprocating saw blade(i.e., a tang on the inner end of the saw blade) and drives the innerend, and thus the saw blade, in a back and forth reciprocating motionthrough a work piece. Reciprocating saw machines are typically driven byelectric motors (e.g., cord or cordless saws), or are pneumaticallydriven. The reciprocating motion can be an orbital cutting action, astraight or linear cutting action, or an angled cutting action.Reciprocating saws are sometimes referred to as recip saws, or jig saws,and reciprocating saw blades are sometimes referred to as recip bladesor jig saw blades. A jig saw includes a handle and a relatively small,thin blade oriented to be used comfortably on horizontal surfaces. Arecip saw usually has a larger blade and blade-mounting assemblyresembling that of a jig saw, but includes a handle oriented to allowthe saw to be used comfortably on vertical surfaces. Well knownreciprocating saws are sold under the brand names “SAWZALL™” byMilwaukee Electric Tool Corporation and “TIGER SAW™” by Porter-CableCorporation.

Some reciprocating saw machines also include a shoe attached to thefront end thereof, having a central opening through which the saw bladeextends. The shoe is adapted to engage a work piece during cutting tostabilize and guide the reciprocating movement of the saw blade into anout of the work piece.

A reciprocating saw blade for use in a reciprocating saw is typicallyelongated having a length selected for a particular cutting application.As mentioned, the inner end of the blade defines a tang for releasablymounting the blade in the chuck of a reciprocating saw, and the outerend of the blade is a free end that engages a work piece. Some recipblades, however, have tangs on both ends, such as described in U.S.patent application Ser. No. 12/396,318, filed Mar. 2, 2009, entitled“Reciprocating Saw Blade with Tangs on each End and Related Method,”which is hereby expressly incorporated by reference in its entirety aspart of the present disclosure. Typical reciprocating saw blades includea cutting edge, extending between the inner and outer ends of the blade,defined by a plurality of cutting teeth spaced relative to each otheralong one side of the blade or some other cutting medium. Often, anon-working edge is formed on an opposite side of the blade relative tothe cutting edge. Some blades, however, have two opposing cutting edges,such as described in U.S. patent application Ser. No. 13/344,647, filedJan. 6, 2012, entitled “Double-Sided Reciprocating Saw Blade and RelatedMethod,” which is hereby expressly incorporated by reference in itsentirety as part of the present disclosure.

A reciprocating saw blade relies, in part, on its tang angle for itseffective cutting action. The tang angle is the angle between the tangand the cutting edge. A positive tang angle increases the cutting angleof the blade. An increased cutting angle generally provides moreaggressive cutting action and thus quicker cutting. However, increasedcutting angle requires more power to start or continue the cut, and canaffect wear and/or durability of the blade. Large cutting angles canalso result in high and even excessive vibration transmitted to theuser, resulting in a poor end user experience that is described as a“rough feel” when using the blade. Therefore, where the design of thecutting portion of the blade and/or the material to be cut can implicatethese effects, tang angle is selected so that the cutting angle of theblade does not exceed an acceptable amount.

Another factor limiting the magnitude of a blade tang angle is the shoeof the saw machine. The tang angle of the blade must be small enough sothat the blade will not interfere with, or cut into, the shoe whilereciprocating through the central opening thereof, thereby damaging theshoe and also unnecessarily increasing blade wear.

Yet another factor that limits the magnitude of the tang angle is thatas the tang angle increases the proximal end of the tang comes closer tothe tooth edge. As many recip saw blades are punched from continuoustoothed strip the proximal end of the tang may intersect the gullets ofthe teeth in the strip. This is undesirable because it reduces the lifeof the punching dies and also creates a discontinuous, notched surfacealong the tang that the end user will regard as a product defect. Thus,it may not be practical or possible to provide a tang angle to achieve adesired effective cutting angle.

SUMMARY

In accordance with one aspect, the present invention is directed to areciprocating saw blade, comprising an elongated blade body defining aninner end and a distal end, a cutting edge located on one side of theblade body, extending between the inner and distal ends thereof, anopposing edge located on an opposing or opposite side of the blade bodyrelative to the cutting edge and a tang located at the inner end of theblade body and projecting therefrom at an acute angle of at least about3° relative to a line tangent to an inner end of the cutting edge,wherein at least a portion of the cutting edge defines a curved contourcurved toward or in the direction of the opposite edge. In someembodiments, the entirety of the cutting edge is curved.

In some embodiments, the cutting edge includes a first portion defininga substantially non-curved contour and a second portion defined by thecurved contour. In some such embodiments, the first portion defines aninnermost portion of the cutting edge. In certain embodiments, the firstportion defines a length of about 1.5 inch. In another embodiment, thesecond portion is located distally adjacent to the first portion. Insome embodiments, the second portion defines a length within the rangeof about 1.5 inch to about 3 inch. In various embodiments, the secondportion curves in a concave direction toward or in the direction of theopposing edge of the blade body.

In yet further embodiments, the cutting edge further includes a thirdportion defining a substantially non-curved contour. The third portioncan be defined by a distal-most portion of the cutting edge. In someembodiments, the third portion defines a length within the range ofabout 1.5 inch to about 3 inches.

In various embodiments, the curved portion curves a maximum distancetoward or in the direction of the opposing edge within the range ofabout 0.030 inch to about 0.200 inch. In some such embodiments, thecurved portion curves a maximum distance toward or in the direction ofthe opposing edge within the range of about 0.030 inch to about 0.120inch. The maximum distance corresponds in some embodiments to anapproximately middle point of the curved portion.

In certain embodiments, the acute angle is within the range of about 3°to about 8°. In some such embodiments, the acute angle is within therange of about 3° to about 6°. Where the tang angle is at least about3°, the saw blades provide increased cutting performance over saw bladesdefining a smaller or zero tang angle.

An advantage of the present invention is that the curvature of thecutting edge further increases the cutting angle with which the cuttingedge engages a work piece. Thus, the “effective” cutting angle at apoint along the cutting edge is created by the combination of the actualtang angle and the angle/degree of curvature of the blade at that point.As the curvature of the cutting edge increases the cutting angle beyondthe actual tang angle, it improves cutting performance even further overconventional saw blades having substantially straight cutting edges. Theinvention provides this cumulatively larger effective cutting anglewhile maintaining a sufficiently small actual tang angle for the bladeto clear the shoe of the saw machine. Therefore, interference or cuttingof the shoe by the saw blade while reciprocating through the centralopening thereof is mitigated by the curvature of the cutting edge, thusreducing unnecessary wear of the blade and mitigating damage to the shoeas well.

A further advantage is provided where the cutting angle changesprogressively, e.g., increases, along the curved portion of the blade.Thus, during the stroke of the saw, the cutting angle changes gradually,providing smoother, progressive cutting and minimizing shock or impactto consecutive teeth. It also permits a cut to be started at theproximal end of the cutting edge, where the cutting angle is thesmallest (e.g., equaling the actual tang angle), so that the cuttingaction at cut initiation (power, vibration, wear, durability, etc.) issimilar to a convention straight blade.

Other objects and advantages of the present invention will become morereadily apparent in view of the following detailed description and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of an embodiment of a reciprocating sawblade having a curved cutting edge; and

FIG. 2 is a schematic side view of another embodiment of a reciprocatingsaw blade having a curved cutting edge.

DETAILED DESCRIPTION

In FIG. 1, a reciprocating saw blade is indicated generally by thereference numeral 10. The reciprocating saw blade 10 includes anelongated blade body 12, defining a tang 14 at an inner end thereof forreleasable engagement with a chuck of a reciprocating saw, and a freeend 16 at an opposing distal end thereof for engagement with a workpiece.

The tang 14 is sized and shaped to allow the blade 10 to be engaged by aclamping device. As should be understood by those of ordinary skill inthe pertinent art, the shape and dimensions of the tang may beconfigured to be compatible with widely used reciprocating saws andchucks, such as, for example, a one-half inch universal tang, or may beconfigured to be compatible with a unique or specific chuck of areciprocating saw, such as, for example, a quick change chuck. As shownin FIG. 1, the tang 14 defines a tang aperture 15 extending through thetang 14. One purpose of the tang aperture 15 is to increase the strengthand otherwise enhance the safety associated with clamping or connectingthe blade 10 to a particular clamping device, e.g., a chuck, by use of aconnecting element, e.g., a stud or pin, extending through the tangaperture 15 whenever the configuration or construction of the clampingdevice permits. Thus, the tang aperture 15 may also be sized, shaped,positioned and/or configured to operatively accommodate any of a varietyof different chucks or like connecting elements.

During operation, when the saw blade is engaged by the chuck or likemechanism of the saw, e.g. via the tang, the reciprocating saw drivesthe saw blade 10 in a reciprocating motion as described above, e.g., aseries of push and pull or forward and return strokes. During eachstroke, the saw blade 10 moves between a rearmost position and a forwardmost position to, in turn, apply a cutting action to a work piece. Thatis, the cutting features of the blade, e.g., the free end 16, move intoengagement with, and through, a work piece.

In order to effectively operate in a reciprocating saw, the blade body12 of the reciprocating saw blade 10 must be sufficiently rigid to allowthe blade 10 to be engaged by the chuck of a reciprocating saw at onlyone end of the blade, while the opposite free end of the blade is drivenin a reciprocating motion into engagement with and through a work piece.In the illustrated embodiment, the blade body 12 is formed of metal,such as, for example, carbon steel or spring steel. However, as shouldbe understood by those of ordinary skill in the art, the blade may beformed of other materials, currently known or that later become know,depending upon the intended cutting application.

The blade body 12 also defines a cutting edge 18 along one elongatedside thereof, extending between the tang 14 and the distal end 16. Inthe illustrated embodiment, the blade body 12 also defines a non-workingedge 19 along the opposing elongated side of the blade body, extendingbetween the tang 14 and the distal end 16. However, as should beunderstood by those of ordinary skill in the art, the blade body mayalternatively define an opposing second cutting edge.

The cutting edge 18 is defined by a plurality of cutting elements orteeth 20, each defining a tooth tip 22. As should be understood by thoseof ordinary skill in the pertinent art, the cutting teeth 20 are adaptedfor respective cutting application(s) based on, for example, theparticular tooth geometries or forms (such as by configuring clearancesurfaces and clearance angles), the pitch or number of teeth-per-inch(“tpi”), sets, and/or the teeth heights or height differentials.Exemplary cutting teeth configurations are disclosed in U.S. patentapplication Ser. No. 12/396,318, filed Mar. 2, 2009, entitled“Reciprocating Saw Blade with Tangs on each End and Related Method”;U.S. Pat. No. 8,210,081, issued Jul. 3, 2012, entitled “ReciprocatingSaw Blade Having Variable-Height Teeth and Related Method,” which, inturn, claims the benefit of similarly titled U.S. Provisional PatentApplication No. 60/934,262, filed Jun. 12, 2007; U.S. patent applicationSer. No. 13/344,647, filed Jan. 6, 2012, entitled “Double-SidedReciprocating Saw Blade and Related Method;” U.S. patent applicationSer. No. 12/776,145, filed May 7, 2010, entitled “Recip Blade withRobust Tooth Form”; and U.S. patent application Ser. No. 12/827,658,filed Jun. 30, 2010, entitled “Saw Blade Tooth Form for Abusive CuttingApplications,” each of which is hereby expressly incorporated byreference in its entirety as part of the present disclosure.

As shown in FIG. 1, the saw blade 10 defines a length L, extending froma tip 21 of the tang 14 at the inner end of the blade body 12 to adistal tip 23 of the distal end 16 of the blade body 12. In someembodiments, the saw blade 10 defines a length L within the range ofabout 4 inches to about 12 inches. In the illustrated embodiment, thesaw blade 10 defines a length L of about 6 inches. However, as should beunderstood by those of ordinary skill in the pertinent art, the lengthof the saw blade 10 may be changed as desired or otherwise required foran intended cutting application.

Straight reference line “A” indicates an imaginary line tangent to thecutting edge 18 at its inner end 6. The tang 14 is oriented at an actualtang angle TA, defined between an elongated bottom edge T of the tang 14relative to the reference line A, as shown in FIG. 1. The tang angle TAorients the cutting edge 18 such that the cutting edge is angleddownwardly at an acute angle relative to the elongated bottom edge T ofthe tang, and thus relative to the reciprocating motion of the saw(regardless of whether the saw reciprocates along or parallel toelongated bottom edge T of the tang). Therefore, the tang angle TAincreases the cutting angle of the cutting edge 18, i.e., the angle withwhich the cutting edge 18 engages the work piece, and enables thecutting edge 18 to more effectively cut work pieces in respectivecutting application(s). As a result, the tang angle facilitatesmaintaining the rake faces or cutting edges of the teeth 20 more fullyengaged with the work piece during and throughout the cutting stroke. Itimparts a more positive effective rake angle on the teeth. Even if theteeth define a 0° or substantially 0° rake angle or a negative rakeangle that is less than the tang angle, the blade will cut with aneffective rake angle that is positive. This increases the cutting actionof the teeth and blade. As may be recognized by those skilled in thepertinent art based on the teachings herein, the tang or cutting anglecan be tuned to the respective cutting edge and/or cutting applicationto optimize the cutting performance of that cutting edge for therespective cutting application or applications of that cutting edge. Inthe illustrated embodiment, the tang 14 defines a tang angle TA withinthe range of about 3° to about 8°. In some embodiments, the tang 14defines a tang angle TA within the range of about 3° to about 6°.

As shown in FIG. 1, the tips 22 of the teeth 20 define a contour of thecutting edge 18 that is shown in FIG. 1 by imaginary line “B.” Thecontour of the cutting edge, i.e., as shown by line B, is curvedconcavely toward or in the direction of the edge 19. In someembodiments, the cutting edge 18 defines at least one substantiallystraight, non-curved portion and at least one curved portion. In theillustrated embodiment, the cutting edge contour B defines 3 adjacentsections or portions. The first section 1, defining an innermost sectionof the cutting edge 18 as shown in FIG. 1, is a non-curved section. Insome embodiments, the length from the tip 21 of the tang 14 to thedistal end of the first section 1 is about 1.5 inch. Thus, inembodiments utilizing a one-half inch universal tang, for example, thefirst section 1 defines a length of approximately 1 inch.

The second, middle section 2, distally adjacent the first section 1,defines a curved portion of the cutting edge 18. The second section 2 iscurved toward or in the direction of the non-working edge 19, i.e., in aconcave manner relative to the reference line A. In some embodiments,the second section 2 defines a length within the range of about 1.5 inchto about 3 inches. In the illustrated embodiment, the second section 2is curved such that at a point thereof, e.g., an approximately middlepoint thereof, it is curved a max distance hmax toward or in thedirection of the rear edge 19. That is, at that point, reference line Bis located a distance h from the reference line A. In the illustratedembodiment, where length L is about 6 inches, the maximum distance hmaxis within the range of about 0.030 inch to about 0.200 inch, and in someembodiments, the maximum distance hmax is within the range of about0.030 inch to about 0.120 inch. For longer or shorter blades, themaximum distance hmax would be proportionally greater or less,respectively, according to the arc length of the blade. It should beunderstood by those of ordinary skill in the art, though, that saidproportionality is not necessarily linearly proportional based on bladelength, because, as indicated above, the relevant parameter is arclength, not linear length. The amount of curvature, e.g., hmax, may beselected according to the particular blade design and cuttingapplication, to achieve desired performance, wear, durability andcutting “feel” of the blade. For example, the inventors have found thatwood cutting applications tolerate a curvature/hmax toward the higherend of the above-discussed ranges.

In the illustrated embodiment, the curvature of the curved section issubstantially constant, i.e., defines a substantially constant radius ofcurvature, such that the distance h by which the cutting edge 18 hascurved substantially equally and progressively decreases in bothdirections from the maximum point of hmax toward the opposing ends ofthe second section 2. In other embodiments, the curvature is notsubstantially constant, but varies along the length of the secondsection 2. For example, the radius of curvature would increase ordecrease, linearly, progressively, or otherwise vary, along the lengthof the second section 2.

The third section 3, adjacent the second section 2, extends from thedistal end of the second section 2 to the distal end 16 of the blade 10.In some embodiments, the third section defines a length within the rangeof about 1.5 inch to about 3 inch. In the illustrated embodiment, thethird section 3 is substantially not-curved. However, as should berecognized by those of ordinary skill in the pertinent art based on theteachings herein, the dimensions of the first, second and third sectionsdefining the cutting edge contour B are exemplary, and may be changed asdesired or otherwise required. For example, for blades that are longerthan 6 inches, the curved portion of the cutting edge, and/or thesubstantially not-curved portion(s), may define a greater length.Alternatively, the either the first and second or second and thirdsections of the cutting edge may combine as one curved section. In yetother embodiments, the entire cutting edge 18 of the blade is curved. Insome embodiments the rear edge 19 is curved, e.g., in like manner as thecutting edge 18.

In FIG. 2, another saw blade is indicated generally by the referencenumeral 110. The blade 110 is substantially similar to the saw blade 10described above in connection with FIG. 1, and therefore like referencenumerals preceded by the numeral “1” are used to indicate like elements.A primary difference of the blade 110 in comparison to the blade 10 isthat the blade 110 is designed for cutting a different material than theblade 10. In the embodiment shown in FIG. 2, the blade 110 is designedfor cutting wood. Accordingly, the blade 110 has a different toothformand different dimensions than the blade 10. However, this embodiment isnot limited to a particular material and can be used to cut a variety ofmaterials that are known or may become known. It should also beunderstood that while the embodiment shown in FIG. 2 includes straightsection 131 toward the inner end and straight section 133 toward thedistal tip 123, other embodiments do not have one or both of thestraight section 131 and straight section 133, where the curved section132 extends to one or both of the inner end and the distal tip 123. Thatis, in some embodiments, the entire cutting edge 118 of the blade 110 iscurved.

One advantage associated with the above-mentioned blade configurations 1s that because the tang defines a tang angle TA greater than about 3°,the saw blades 10, 110 provide increased cutting performance over sawblades defining a smaller or zero tang angle. Another advantageassociated with the above-mentioned blade configurations is that thecurvature of cutting edge 18 further increases the cutting angle withwhich the cutting edge 18 engages a work piece. Thus, the “effective”cutting angle at a point along the cutting edge is created by thecombination of the actual tang angle TA and the angle/degree ofcurvature of the blade at that point. For example, as shown in FIG. 1,straight reference line “C” indicates an imaginary line tangent to apoint D along the curved section of the cutting edge 18. The effectivecutting angle TC at point D, defined between the elongated edge T of thetang 14 relative to the reference line C, is the sum of the actual tangangle TA and the angle of curvature of the blade at the point D, e.g.,relative to line A. As the curvature of the cutting edge 18 increasesthe cutting angle beyond the actual tang angle TA, it improves cuttingperformance even further over conventional saw blades havingsubstantially straight cutting edges. The invention provides thiscumulatively larger effective cutting angle while maintaining asufficiently small actual tang angle TA for the blade to clear the shoeof the saw machine. Therefore, interference or cutting of the shoe bythe saw blade 10 while reciprocating through the central opening thereofis mitigated by the curvature of the cutting edge, thus reducingunnecessary wear of the blade 10 and mitigating damage to the shoe aswell.

Another advantage is that cutting angle changes progressively, e.g.,increases, along the curved portion of the blade. Thus, during thestroke of the saw, the cutting angle changes gradually, providingsmoother, progressive cutting and minimizing shock or impact toconsecutive teeth. It also permits a cut to be started at the proximalend of the cutting edge, where the cutting angle is the smallest (e.g.,equaling the actual tang angle), so that the cutting action at cutinitiation (power, vibration, wear, durability, etc.) is similar to aconvention straight blade.

Accordingly, the invention achieves unexpected results previously notthought possible in the industry and by those of ordinary skill in theart. It was previously thought by those of ordinary skill in thepertinent art that the larger effective cutting angle provided by thecombination of a higher tang angle and a curved blade, as describedherein, would too aggressively affect blade wear and/or durability ofthe saw blade. Similarly, it was thought that such a combination wouldrequire excessive power by a user to start or continue a cut.Accordingly, it was believed and taught that where a non-straight bladewas used, the tang angle should be reduced to a small angle,significantly smaller than the tang angle used in an equivalent straightblade (e.g., a straight blade having, for example, a similar toothprofile). However, contrary to previous teachings and conventionalwisdom, the inventors have unexpectedly found that the combination of alarger tang angle TA and the concave curvature of the blade as describedherein provides increased cutting performance without excessivedetriment to blade wear, blade durability, or ease of starting and/orcontinuing a cut.

It should be understood that the term “about” and like terms used hereinwhen referring to a dimension or characteristic of blades of theinvention indicate that the described dimension/characteristic is not astrict boundary or parameter and does not exclude variations therefromthat are functionally similar. At a minimum, such references thatinclude a numerical parameter would include variations that, usingmathematical and industrial principles accepted in the art (e.g.,rounding, measurement or other systematic errors, manufacturingtolerances, etc.), would not vary the least significant digit.

As may be recognized by those of ordinary skill in the pertinent artbased on the teachings herein, numerous changes and modifications can bemade to the above-described and other embodiments of the presentinvention without departing from the scope of the invention as definedin the appended claims. For example, the cutting edge can have one ormore bends along the cutting edge to effect a change in cutting angle,rather than defining a curved portion of the cutting edge. This could beaccomplished, by way of example only, by actually bending the blade inthe desired direction, e.g., in the plane of the blade, or by punchingor machining the cutting edge of the blade to have such bend(s).Accordingly, the portion of the cutting edge distal of the bend willengage a work piece at a cutting angle greater than the portion of thecutting edge proximal of the bend. The cutting angle of the bent portionis defined as the sum of the tang angle and the total bend angle of thebent portion, e.g., the cumulative bend relative to the proximal end ofthe cutting edge. Though in such embodiments the change of cutting anglewill be discrete and not continuous as with a curved cutting edge, thenumber of bends and the amount (degree) of each bend can be selected soas to not overly detrimentally affect saw operation, as should beunderstood by those of ordinary skill in the art. By altering, e.g.,increasing, the cutting angle in such a step-wise fashion, the benefitsof the invention can be achieved.

As another example, the saw blades may include two tangs and two cuttingedges on opposing sides of the blade body. One tang would be used todrive a first cutting edge of the blade and define an effective tangangle for the first cutting edge. The other tang would be used to drivethe second cutting edge of the blade and define an effective tang anglefor the second cutting edge. One cutting edge may be substantiallystraight, and the other cutting edge may be substantially curved.Alternatively both cutting edges may be substantially curved. As anotherexample, in some embodiments, the cutting edge may be defined by cuttingteeth, such as carbide tipped, bi-metal, or traditional carbon steelteeth. In addition, the saw blades of the present invention may becoated with any of numerous different coatings that are currently knownor that later become known, such as a titanium nitride coating (TiN), oran aluminum titanium nitride coating (AlTiN). Accordingly, this detaileddescription of embodiments is to be taken in an illustrative, as opposedto a limiting sense.

What is claimed is:
 1. A reciprocating saw blade, comprising: an elongated blade body defining an inner end and a distal end; a tang coupled to the inner end of the blade body and projecting therefrom, the tang defining an elongated bottom edge; a cutting edge located on one side of the blade body, extending between the inner end and the distal end; and a non-cutting edge located on an opposite side of the blade body relative to the cutting edge and extending between the inner end and the distal end; wherein at least a portion of the cutting edge defines a curved portion that is concavely curved toward the non-cutting edge, a first tangent line to the cutting edge at the inner end is at an acute first angle relative to the elongated bottom edge of the tang, a second tangent line to the curved portion at an intermediate point between the inner end and the distal end is at an acute second angle relative to the elongated bottom edge of the tang, the second angle greater than the first angle, and an entirety of the cutting edge is angled downwardly relative to the elongated bottom edge.
 2. The reciprocating saw blade of claim 1, wherein the curved portion comprises substantially an entirety of the cutting edge.
 3. The reciprocating saw blade of claim 1, wherein the cutting edge includes a first non-curved portion extending from the inner end to a first point and a second portion that includes the curved portion extending from the first point toward the distal end.
 4. The reciprocating saw blade of claim 3, wherein the first portion has a first length and the second portion has a second length that is greater than the first length.
 5. The reciprocating saw blade of claim 3, wherein the second portion extends from the first point to a second point that is closer to the distal end than the first point, and the cutting edge further includes a third non-curved portion extending from the second point to the distal end.
 6. The reciprocating saw blade of claim 1, wherein the curved portion is curved by a maximum distance toward the non-cutting edge of 0.030 inches to 0.200 inches.
 7. The reciprocating saw blade of claim 6, wherein the maximum distance is located at an approximately middle point of the curved portion.
 8. The reciprocating saw blade of claim 1, wherein the first angle is at least 3°.
 9. The reciprocating saw blade of claim 8, wherein the first angle is at most 6°.
 10. The reciprocating saw blade of claim 1, wherein the second angle defines an effective cutting angle at the intermediate point that is equal to a sum of the first angle and an angle of curvature of the blade at the intermediate point.
 11. A reciprocating saw blade comprising: an elongated blade body defining an inner end and a distal end; a tang coupled to the inner end of the blade body and projecting therefrom, the tang defining an elongated bottom edge; a cutting edge located on one side of the blade body, extending between the inner end and the distal end, the cutting edge defining a non-curved first portion extending from the inner end to a first point between the inner end and the distal end and a curved second portion extending from the first point toward the distal end; and a non-cutting edge located on an opposite side of the blade body relative to the cutting edge and extending between the inner end and the distal end, wherein the second curved portion is concavely curved toward the non-cutting edge, such that an entirety of the second curved portion is angled downwardly relative to the elongated bottom edge.
 12. The reciprocating saw blade of claim 11, wherein the first portion extends along a first straight line at an acute first angle relative to the elongated bottom edge of the tang.
 13. The reciprocating saw blade of claim 12, wherein the first angle is at least 3°.
 14. The reciprocating saw blade of claim 13, wherein the first angle is at most 6°.
 15. The reciprocating saw blade of claim 12, wherein a second line tangent to the curved second portion of the cutting edge at an intermediate point between the first point and the distal end is at an acute second angle relative to the elongated bottom edge of the tang, the second angle greater than the first angle.
 16. The reciprocating saw blade of claim 15, wherein the second angle defines an effective cutting angle at the intermediate point that is equal to a sum of the first angle and an angle of curvature of the blade at the intermediate point.
 17. The reciprocating saw blade of claim 11, wherein the first portion has a first length and the second portion has a second length that is greater than the first length.
 18. The reciprocating saw blade of claim 11, wherein the second portion extends from the first point to a second point that is closer to the distal end than the first point, and the cutting edge further includes a non-curved third portion extending from the second point to the distal end.
 19. The reciprocating saw blade of claim 11, wherein the curved portion is curved at a maximum distance toward the non-cutting edge of 0.030 inches to 0.200 inches.
 20. The reciprocating saw blade of claim 19, wherein the maximum distance is located at an approximately middle point of the curved portion. 